Apparatus for treating paper



Feb. 11, 1941. L. E. LOVETT APPARATUS FOR TREATING PAPER Original FiledSept. 8, 1933 INVENTOR Laws 15. Lav/:77 /i%zf a 1 Patented Feb. 11, 1941UNITED STATES PATENT OFFICE APPARATUS FOR TREATING PAPER Louis E.Lovett, Cleveland Heights, Ohio, assignor to Industrial RayonCorporation, Cleveland, Ohio, a corporation of Delaware 7 Claims.

This application is a division of application Serial No. 688,643, filedSeptember 8, 1933, for Method and apparatus for treating paper.

In the manufacture of sheets from materials which possess the propertyof becoming plastic under heat and/or pressure, such as cellulosenitrate, cellulose acetate, cellulose formate and the like, the sheet iscustomarily formed as a single thin film. Where it is desired to make upcontainers, transparent or otherwise, from the sheet, such as bags orsacks for peanuts and other food products, it is necessary to join theedges of a sheet or sheets together in some manher to constitute the bagor sack. This has heretofore been accomplished by sealing the sheetstogether at their edges by means of some adhesive which is spreadbetween the sheets. If a transparent container is desired, the adhesiveis likely to reduce the transparency of the container where applied and,in any case, detracts from its appearance. It has now been iound thatsheets composed of a compound which becomes plastic when heated, such ascellulose acetate, cellulose nitrate, etc., may be so affected by theapplication of a heated element thereto that the material at the pointof application softens and flows so as to join adjacent sheets togetherby a bond consisting of the substance of the sheets. That is to say, noseparate adhesive medium is necessary to seal sheets of material of thiskind together but, on the contrary, the substance of the sheetsthemselves can be used as the ad hesive. In this way, one or two or moresheets can be sealed together around their edges to constitute acontainer which is transparent or opaque according to the nature of thematerial chosen.

It is an object of the present invention to provide a method of sealingtogether the edges of one or more sheets composed of a substance capableof becoming plastic under heat and/or pressure, the sheets being joinedtogether through the coherence of their own substance. Another object ofthe invention is to provide a container, transparent or otherwise,consisting of one or more sheets of material having the property ofbecoming plastic under heating and joined together into container formalong the margins by the uniting of the substance of the adjacentsurfaces. A further object of the invention is to provide an apparatusfor readily sealing a plurality of sheets together, with or withoutimpressing a legend or design on the sheets.

The invention is useful in wrapping loaves of bread in a bakery where itis desired to use for wfrapping purposes sheets of material of thenature of cellulose acetate and the like. Where waxed paper is used forwrapping bread, the ends of the wrapped loaf are brought into contactwith a heated surface which melts the paraffin with which the paper isimpregnated and subsequent cooling seals the loaf in the wrapper. Thisis not possible with cellulose acetate and the like since the heatedsurface tends to stick and cause crumpling and tearing. The rotatableheating element forming part of the invention may advantageously be usedfor this purpose since it rolls freely and, while imparting heat theretofor the purpose of forming a seal, does not stick to the wrappingmaterial.

It is, however, difficult to maintain a constant heat in such a rotatingelement, as must be done if the device is to be continuously operative.To accomplish this purpose, apparatus of the type illustrated in theaccompanying drawings has been devised. Such apparatus comprises atransformer in which a primary circuit connected to a source ofalternating current produces a magnetic flux in a core upon one side ofwhich is wound said primary circuit and upon the other side of which ismounted the rotatable heating element, which constitutes a secondarycircuit and is heated by induced current passing there through in anaxial direction. In this way, such element can be rotated continuouslywithout interference with its movement by the necessary heating means.

Such an electrically heated device can assume various forms, as will beapparent, and two such forms have been set forth in the accompanyingdrawing for purposes of illustration. In said drawing: Fig. l is aperspective of a heating device suitable for hand use as applied tosheets capable of being sealed together by their own substance; Fig. 2is an enlarged transverse section taken through the device shown in Fig.1; Fig. 3 is a diagrammatic View of a machine embodying the principlesof the invention and suitable for larger scale production; and Fig. 4 isan end view of the apparatus shown in Fig. 3.

Referring to Figs. 1 and 2 of the drawing, the apparatus there shown isintended for manual use and comprises a ring i of steel or othersuitable material mounted on a laminated transformer core 2 by means ofa bearing 3 of heatresisting material. Around the opposite side of thecore 2 is disposed a primary winding 4 to which current may be suppliedthrough the leads 5. An alternating current passing through the primarywinding 4 will induce a secondary current in the ring I. Since the ringin effect constitutes a winding of but a single turn, it will becomeheated by the induced current and this heat can be imparted to the edgesof two superimposed sheets 6 of a material capable of being self-sealed,such as cellulose acetate film.

The device can be manipulated and pressure applied by means of thehandle 1 through which the lead wires 5 may be passed. Since the heatfor the ring I arises from the induced current therein, there are noparts which require contact with the ring in order to transmit heatthereto and it is free to rotate on its bearing 3. Consequently, thedevice can be rolled over the edges of the double sheet 6 continuouslywithout stopping to reheat the heating element. A suitable casing l I issupplied in order to cover the various parts of the transformermechanism, the ring I projecting through a slot 12 provided in suchcasing for the purpose.

If it is desired to apply a legend 8 to the sheet, correspondingcharacters 9 may be formed in the periphery of the ring I, in reverse,and the heating element will then impress the desired legend as it sealsthe two sheets together.

The action of the heating element is to soften or melt the material ofwhich the sheet is made up, examples of such materials being cellulosenitrate, cellulose acetate, cellulose formate and the like. The materialof each sheet then joins with the material of the neighboring sheet andthe two are securely sealed together by their own substance, theplasticized material setting immediately after the removal of the heatand pressure. The sealing operation may be performed around the edges ofthe sheets or both around the edges and across the width at regularintervals, the composite sheet then being severed at the transverselysealed strips in order to provide a number of smaller sheets sealedaround their edges which can be made up into bags.

For certain types of work on which it is desired to perform the sealingoperation more rapidly, the device illustrated in Figs. 3 and 4 may beemployed. It comprises a ring l3 rotatably mounted about one side of atransformer core so as to be electrically heated in a manner similar tothat of rin I in the device of Figure 1. Ring l3 projects through a slotH in a casing l5 which is mounted in a frame I6. A table [1 ispositioned beneath the ring I3 and is slotted to receive a portion of aroller 18 mounted therebelow. Roller I8 is driven by a motor I9 througha gear box 2| and contacts with the ring l3 which is urged thereagainstby a spring 22. Sheets composed of the above-mentioned materials or of amaterial having similar properties are laid on the table l1 and passedbetween the ring l3 and the roller l8 to be quickly sealed togetheralong their edges by the heat from the ring I3 under the pressureexerted by the spring 22.

The invention is thus applicable to the manufacture of bags or othercontainers, such as bread wrappers, made from sheet materials having theproperty of becoming plastic under heat and/or pressure, especiallywhere a transparent wrapper is desired. The cellulose esters areexamples of suitable materials from which such sheets may be made up andpossess the property of joining together when heated, with or withoutthe application of pressure. The rotatable heating means is especiallydesirable in handling such materials since the plastic nature of theheated sheet causes it to stick to the surface of any heating elementwhich is not rotatable.

It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever ieatures of patentable novelty reside inthe invention.

What is claimed is:

1. Sealing apparatus comprising a core; a primary winding on said core;bearing means disposed about said core; and, rotatably mounted upon saidbearing means, a metallic ring adapted to be heated by induced currentconstituting a closed secondary circuit in relation to said primarywinding, said ring being so disposed that it has rolling contact withthe material to be sealed.

2. Sealing apparatus comprising a core; a primary winding disposed aboutone portion of said core to which primary winding is supplied analternating current; bearings disposed about another portion of saidcore; and, rotatably mounted on said bearings, a steel ring which inrelation to said primary winding constitutes a closed sec ondarycircuit, said ring being heated by induced current.

3. Sealing apparatus comprising a core; a primary winding disposed aboutone portion of said core to which primary winding is supplied analternating current; bearing means disposed about another portion ofsaid core; and a metallic ring constituting a closed secondary circuitrotatably mounted on said bearing means, said ring bearing upon itsperiphery a plurality of characters so disposed that said characterscontact with and impress a legend into the material to be sealed.

4. A branding device comprising a transformer core, a primary windingassociated therewith, and a branding wheel comprising a metallic annulushaving branding portions rotatably mounted with reference to the core sothat most of the magnetic flux produced in the latter passes through thewheel in a substantially axial direction to heat the same by inducedcurrent.

5. A branding device comprising a transformer core, a primary windingassociated therewith, and a branding wheel comprising a metallic annulusjournalled on the core so that most of the magnetic flux produced in thelatter passes through the wheel in a substantially axial direction toheat the same by induced current.

6. Sealing apparatus comprising a housing enclosing a transformer core,a primary circuit disposed about one side of said core, and a rotatablemetallic ring mounted about the other side of said core constituting asecondary circuit, said ring having at least a portion of itscircumference extending through said housing.

'7. Sealing apparatus comprising a housing enclosing a transformer core,a primary circuit disposed about one side of said core, and a rotatablemetallic ring mounted about the other side of said core constituting asecondary circuit, said ring having at least a portion of itscircumference extending through said housing; a roller outside saidhousing; and means for supporting said housing in such manner that saidmetallic ring is maintained in juxtaposition to said roller.

LOUIS E. LOVETT.

